Port Miami Dredge Project

An analysis of how many corals were killed – and what killed them

How is it that ten years after the completion of the Port Miami Dredging Project, there is still something new to discover about what happened to corals? Simply, that’s how science sometimes works. Experiments are repeated, mistakes are corrected, and new information becomes available. In our case, new people joined together and challenged assumptions, re-analyzing old data sets.

A series of peer-reviewed publications appeared after dredging was completed, examining what caused coral mortality during the project. While everyone agrees that corals were killed by sediment plumes from dredging, the number of corals killed remains controversial. A major confounding event was the onset of a coral disease epidemic concurrent with dredging operations. The disease was new and catastrophically deadly. As a result, many agency personnel and scientists were slow to understand its impact. Dredging is well-known to be dirty and damaging to coral.

Therefore it’s easy to understand that there was reluctance to accept that something besides dredging might be killing corals. In some cases it took years for people to realize that the disease had an overwhelming impact on corals not just at the dredge site, but regionally and eventually throughout the Caribbean.

Resolution of the controversy is necessary because millions of taxpayer dollars are at risk if additional mitigation is required to account for more corals killed than originally predicted by the Florida Department of Environmental Protection. The following peer-reviewed papers show the timeline of the decade-long conflict over how many corals dredging killed. Brief summaries (and links) highlight each paper’s conclusion. We recently drafted a new paper that re-analyzed modeling that claimed 560,778 corals were killed, and we also presented new results using data from baseline and post-dredging surveys that were previously available only in project reports.